The new record of two terebrid gastropods, Terebra (Dimidacus?) succinea and T. (Decorihastula) kilbuni collected from the west of Kushimoto, at the tip of the Kii Peninsula, are reported ; the former species extends distribution further north from Okinawa, the later from Hawaii. The 52 terebrid species have been found so far around Shionomisaki.

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Chromosomes of four species in Pectinidae (Bivalvia, Pteriomorphia) were studied by squash method of eggs and chopping method of trochophore larvae and gills of adults. Chromosome numbers and karyotypes were as follows : Chlamys nobilis (2n=32) ; 6M+26T Ch. farreri farreri (2n=38) ; 8(M, SM)+12(SM, ST)+18(ST, T) Pecten albicans (2n=38) ; 4(M, SM)+6(SM, ST)+28T Patinopecten yessoensis (2n=38) ; 14(M, SM)+18(SM, ST)+6T

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Vertical variation in size structure and density of the littoral fringe periwinkle, Nodilittorina exigua was investigated. Individuals larger than 4 mm in shell height were at lower levels in June and July than in May and August. The recruits appeared in August in lower part of N. exiguazone and their range extended upward in later months. The older year-classes were distributed approximately in equal density vertically in June and July but gathered at higher levels in August. Female percentage was approximately the same as that of male's through the year except in winter, when female percentage significantly exceeded that of male's. Females occupied lower positions than males through the year. In the distribution zone of N. exigua, individuals at high level tended to move downward and those at low level upward, so that their distribution was maintained within a certain range without dispersion. Mean size of the snails was larger at higher levels in all the seasons except summer. This shore-level size gradient was thought to be maintained by differential movement of the different sized snails.

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The production of the major cohort of the population of the mussel Mytilus galloprovincialis collected along the seashore of Suma, Kobe, was calculated. The daily production in live weight was initially 200g/m^2 reaching 430g/m^2 at its maximum, and then gradually decreased. Production in live weight reached 169kg/m^2/3.42 years. The production of dry flesh, excluding the inorganic matter, was 9.342kg/m^2/3.42 years, and the production of organic matter in shells was 2.304kg/m^2/3.42 years. Converted to a caloric value from them the production of dry flesh was 49, 998kcal/m^2/3.42 years, and the production of the organic material in shells was 13, 016kcal/m^2/3.42 years. The addition of both organic production was 11.646kg/m^2/3.42 years and, 63, 014kcal/m^2/3.42 years in caloric production. The proportion of production in each year was, in total caloric production, 70.0% in the 1st year, 21.9% in the 2nd, 7.7% in the 3rd, and as small as 0.27% in the 4th year. The average biomass in live weight was 29.26kg/m^2 and 1.571kg/m^2 in dry flesh weight including ash. The turn-over rate was 5.781 and was calculated from the live weight, and 6.624 was obtained from measurement of the dry flesh weight including ash.

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The four Japanese species of the genus Hemizaptyx, H. pinto (Pilsbry, 1901) from Yakushima Island, H. ptychocyma (Pilsbry, 1901) from Yakushima Island, H. purissima (Pilsbry, 1905) from Hachijojima Island and H. takarai (Kuroda, 1960) from Uotsurijima Islet of Senkaku Islands, are described and illustrated in viewpoint of morphology of shell, clausilium, genitalia and geographic distribution.

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[in Japanese]

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